GB244924A - An improved process for the refining of saccharine liquids - Google Patents

Abstract

244,924. Singh, P., and Majithia, S. K. S. Jan. 6, 1925. Purifying saccharine liquids.-Sugar-containing liquids are clarified and bleached by first precipitating aluminium hydroxide therein by adding aluminium sulphate or other suitable aluminium salt and then adding the requisite amount of alkali, such as caustic soda, sodium carbonate or milk of lime, to give a slightly alkaline reaction, and heating preferably to 100‹ C. and separating the precipitated matter. The liquid is then acidified and is boiled with a clarifying and bleaching agent, which will decompose on heating into sulphur dioxide and a metallic hydroxide, and the precipitated matter separated. In some cases the treatment with the clarifying and bleaching agent may be repeated. The sugar-containing liquids may be subjected to preliminary treatment by sieving or other known methods to remove easily eliminated impurities. In the first part of the process the liquid is preferably made alkaline before adding the aluminium sulphate, and before the filtration, kieselguhr or other suitable clayey or like substance may be added to form porous, easily washed filter cakes. The clarifying &c. agent may consist of a suitable metallic hydroxide dissolved or suspended in an aqueous sulphur dioxide solution. In the example given. it is prepared by precipitating aluminium hydroxide from a dilute aluminium sulphate solution with the required amount of caustic soda or sodium carbonate, washing the precipitate almost free from sodium sulphate, and suspend. ing it in water and passing sulphur dioxide therethrough until a clear solution with a strong odour of sulphur dioxide is obtained. This solution is an acid solution of sulphates and contains basic aluminium sulphate Al2 (SO,), 6A1 (OH)3 aluminium sulphite, and a little sodium sulphate.